Iron tapped from the blast furnace is pig iron, and contains significant amounts of carbon and silicon. To produce malleable wrought iron, it needs to undergo a further process. In the early modern period, this was carried out in a finery forge. There were several types of finery forges. The dominant type in Sweden was the German forge, which had a single hearth that was used for all processes. General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ... Blast furnace diagram A blast furnace is a type of furnace for smelting metal ore. ... Pig iron is raw iron, the immediate product of smelting iron ore with coke and limestone in a blast furnace. ... General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Atomic mass 12. ... General Name, Symbol, Number silicon, Si, 14 Chemical series metalloids Group, Period, Block 14, 3, p Appearance dark gray, bluish tinge Atomic mass 28. ... A wrought iron railing in Troy, New York. ...

In Uppland north of Stockholm and certain adjacent provinces, another kind known as the Walloon forge was used, mainly for the production of a particularly pure kind of iron known as örgrund iron, which was used in England to make blister steel. Its purity depended on the use of ore from the Dannemora mine. The Walloon forge was virtually the only kind used in Great Britain. This had two kinds of hearth, the finery and the chafery. In the finery, the finer remelted pig iron so as to oxidise the carbon (and silicon). This produced a lump of iron (with some slag) known as a bloom. This was consolidated using a water-powered hammer (see trip hammer) and returned to the finery. The next stages were undertaken by the hammerman. His work was to draw the bloom out into a bar to produce what was known as bar iron. In the course of doing so, he had to reheat the iron, for which he used the chafery. The fuel in the finery had to be charcoal, because impurities in any mineral fuel would affect the quality of the iron. Uppland ( â–¶) is a historical province or landskap on the eastern coast of Sweden. ... The Old town in Stockholm from the air (help· info) is the capital of Sweden, located on the east coast at the entrance of lake Mälaren. ... The old steel cable of a colliery winding tower Steel is a metal alloy whose major component is iron, with carbon being the primary alloying material. ... Pig iron is raw iron, the immediate product of smelting iron ore with coke and limestone in a blast furnace. ... A triphammer, sometimes called a tilt hammer, is a massive power hammer, usually raised by a cam and then released to fall under the force of gravity. ...

This is an obsolete process. The finery forge process began to be replaced from the late 18th century by others, of which puddling was the most successful. These used mineral fuel (coal or coke), and freed the iron industry from its dependence on the speed of growth of trees. That transition is the industrial revolution for the iron industry. Coal is a fossil fuel extracted from the ground by underground mining or open-pit mining (surface mining). ... Look up coke in Wiktionary, the free dictionary. ...

references

H. Schubert, History of British iron and steel industry c.450 BC to AD 1775 (1957), 272-291 A. den Ouden, 'The production of wrought iron in finery hearths' Historical Metallurgy 15(2) (1981), 63-87 and 16(1) (1982), 29-33. K-G. Hildebrand, Swedish iron in the seventeenth and eighteenth centuries: export industry before industrialization (Stockholm 1992). P. King, 'The cartel in oregroudns iron: trading in the raw material for steel during the 18th century' Journal of Industrial History 6 (2003), 25-48.